This invention generally relates to fiberous mats to be applied over soil to provide a favorable growth medium for seeds or seedlings. More particularly, it relates to a relatively thin laminated mat of lignocellulose fiber or the like bound with a preferably water soluble or water dispersible adhesive and an improved apparatus and process for manufacturing such a mat.
It is well known that the growth rate and chances of survival of a seedling can be greatly improved if the soil immediately surrounding it is covered with a mulch. Among the varieties which can benefit from such treatment are conifers, fruit trees and grapes. The mulch will prevent erosion, retain moisture and nutrients, suppress the growth of competing vegetation and provide some protection against the extreme temperature changes. Materials which have been used for this purpose range from loose dry straw to mixtures of various ingredients added to water and sprayed on the soil. Protective soil coverings have also been made in the form of mats using materials such as paper, cardboard and plastic.
It is also known to incorporate viable seeds and fertilizers in a fibrous mat during the manufacturing process. A mat of this type provides an ideal medium for germination as well as protection and stimulation for the resulting seedling.
While these various soil coverings ideally should provide for more efficient growth of trees and vegetation, each has inherent limitations which have limited its usefulness. The use of loose material such as straw, while simple and inexpensive, tends to be ineffective because the material can be rather easily washed or blown away. Materials which require bulky or heavy equipment to spread are usually not practical for use in remote or limited access areas. Paper or cardboard mats are inexpensive and easy to handle but do not conform well to the soil and are prone to deform and blow away. Mats made of biodegradable fibers are ideal but have proven to be difficult and expensive to manufacture. They must be flexible enough to conform to the contours of the soil and yet cohesive enough to permit handling. It is desirable that they be relatively thin and of fairly uniform density. If the mats are to contain seeds it is generally desirable to laminate them but the laminating processes formerly used have required costly materials and complex machinery and have resulted in a costly product.
Accordingly it is an object of this invention to provide for a relatively thin, low density mat of lignocellulose fibers which will function as a self-contained support system for an established seedling. It is also an object of this invention to provide for such a mat as a medium for the germination of a viable seed.
It is a further object of this invention to provide a practical and economical method and apparatus for manufacturing such a mat.